Working with DOS Applications

In 1981, Microsoft released MS-DOS for IBM and IBM-compatible PCs. A single-tasking operating system with a command-line interface, MS-DOS managed program execution, oversaw file maintenance, and controlled operations such as disk I/O and keyboard input. By tech age standards, this might seem like ancient history and of little relevance to the world of Windows XP. Yet DOS has not been totally relegated to the annals of electronic history, and Windows XP makes room for those legacy DOS applications through the Virtual DOS machine (VDM) environment subsystem.

The VDM mimics the hardware and software of an MS-DOS computer. When you run a DOS application, Windows XP runs it through the VDM, which allows Windows XP to emulate the DOS operation and translate the program's requests into Windows XP commands.